230 ELEMENTS OF ELECTRICAL ENGINEERING. 



type of engine than is assumed as a basis for Figs. 138 and 139, 

 so as to reduce the cost of coal. 



99. Examples of installation and operation costs. The general 

 averages of cost which are given in Figs. 138, 139 and 141 

 would be misleading without a few actual examples to show how 

 widely costs vary in particular cases. 



Installation costs. The accompanying table of costs gives 

 actual cost data on seven electric power stations not including any 

 part of the distributing system. Total costs are all given in 

 thousands of dollars. The figures which follow Max. and Min. 

 are the extremes of variation of cost per kilowatt capacity under 

 ordinary conditions. Wide deviations from these figures in the 

 actual plants are due to unusual conditions. Thus the land for 

 plant No. 5 which is in a large city cost $43,000; this plant has 

 very expensive foundations of concrete on piling, and its engine 

 capacity aggregates 4,500 indicated horse-power when perhaps 

 3,500 horse-power would be sufficient. The cost per kilowatt 

 of the various parts of the station equipment is in each case the 

 total cost divided by the capacity in kilowatts of the generators 

 installed. 



Operation costs. * The accompanying table of operation costs 

 is taken from the records of two lighting stations for one year. 



Station A is a 225 kilowatt plant owned and operated by a city 

 of 7,000 inhabitants in Connecticut. The equipment includes 

 a 150 kilowatt alternator and a 75 kilowatt alternator each belted 

 to a separate engine. The entire plant represents an investment 

 of $62,512 of which $37,674 is in the building and the equip- 

 ment of the station, and $24,838 is in the distributing system 

 including the transformers. The total number of lamps installed 

 is 9,000 1 6 candle-power incandescent lamps and 107 arc lamps. 

 The cost of trimming and cleaning the arc lamps ($230.79) is not 



*The Electrician (London) publishes each year a digest of the data on operation 

 costs which electric lighting stations are required by law to report to the Board of 

 Trade. These digests contain much valuable information. See also " Cost of Genera- 

 tion and Distribution of Electrical Energy" by Robert Hammond, Journal Institu- 

 tion of Electrical Engineers, Vol. 27, pp. 246-437, 1898. 



